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Author Safar, H.; Pastoriza, H.; Cruz, F. de la; Bishop, D.J.; Schneemeyer, L.F.; Waszczak, J.V.
Title Bulk phase transition in YBa$2$Cu$3$O7-δ single crystals Type Journal Article
Year 1991 Publication (up) Phys. Rev. B Abbreviated Journal
Volume 43 Issue 16 Pages 13610-13613
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Abstract Precise magnetization measurements of YBa$2$Cu$3$O7-δ single crystals have found evidence for a bulk phase transition a few degrees below the superconducting critical temperature. The phase transition is indicated by a sudden drop of the lower critical field , $H_C1(T)$, separating a full coherent state at low fields and temperatures, the Meissner state, from a region at higher temperatures where magnetic excitations are induced at $H=0$.
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Notes Approved no
Call Number BT @ hernan @ safar91 Serial 41
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Author Rodriguez, D.S.; Rodriguez, E.; Luzuriaga, J.; Waszczak, J.V.; Cheong, S.W.
Title Role of anisotropy in the vortex lattice of superconductors high-Q oscillator measurements in 2H-NbSe2 and La1.825Sr.075CuO4 Type Journal Article
Year 1994 Publication (up) Physica C Abbreviated Journal
Volume 229 Issue 1-2 Pages 59-64
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Abstract Measurements of the response of the flux-line lattice in NbSe2 and La1.825Sr0.075CuO4 show important differences between these two materials. In particular, we have studied the magnetic-field and angular dependence of the response of a high-Q mechanical oscillator in fields of up to 1 T. The features seen in NbSe2 seem to be well explained in terms of a change in the pinning regime, usually termed the ''peak effect'' in the critical current, using the collective-pinning model of Larkin and Ovchivnikov within Ginzburg-Landau anisotropic theory. On the other hand the behavior found in the high-T(c) material LSCO seems to fall naturally into a description which takes into account the possibility of phase transitions in the vortex lattice and the quasi-two-dimensional character of the superconductivity.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Medium
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Notes ISI:A1994PF49500008 Approved no
Call Number BT @ hernan @ Serial 252
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Author Safar, H.; Durán, C.; Guimpel, J.; Civale, L.; Luzuriaga, J.; Rodríguez, E.; de la Cruz, F.; Fainstein, C.; Schneemeyer, L.F.; Waszczak, J.V.
Title Logarithmic to nonlogarithmic flux creep transition and magnetic flux hardening in BiSrCaCuO superconducting ceramics Type Journal Article
Year 1989 Publication (up) Physica C: Superconductivity Abbreviated Journal
Volume 162-164, Part 1 Issue Pages 665-666
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Abstract A sharp temperature and field dependent transition from a logarithmic to a non-logarithmic flux creep behavior has been found in BiSrCaCuO superconductors. The transition is not followed by any noticeable change in the magnetization. However, vibrating reed measurements show that it coincides with a strong hardening of the magnetic structure. The transition occurs at fields and temperatures well below the reversibility line. The possible relation to the recently proposed flux lattice melting is discussed.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ jguimpel @ Serial 626
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Author Safar, H.; Durán, C.; Guimpel, J.; Civale, L.; Luzuriaga, J.; Rodriguez, E.; de la Cruz, F.; Fainstein, C.; Schneemeyer, L.F.; Waszczak, J.V.
Title Logarithmic-to-nonlogarithmic flux-creep transition and magnetic-flux hardening in Bi-Sr-Ca-Cu-O superconducting ceramics Type Journal Article
Year 1989 Publication (up) Physical Review B Abbreviated Journal Phys. Rev. B
Volume 40 Issue 10 Pages 7380
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Abstract A sharp temperature- and field-dependent transition from a logarithmic to a nonlogarithmic flux-creep behavior has been found in Bi-Sr-Ca-Cu-O superconductors. The transition is not followed by any noticeable change in the magnetization. However, vibrating-reed measurements show that it coincides with a strong hardening of the magnetic structure. The transition occurs at fields and temperatures well below the reversibility line. The possible relation to the recently proposed flux lattice melting is discussed.
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Publisher American Physical Society Place of Publication Editor
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Notes Approved no
Call Number BT @ jguimpel @ 10.1103/PhysRevB.40.7380 Serial 627
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Author Safar, H.; Pastoriza, H.; Guimpel, J.; Cruz, F. de la; Bishop, D.J.; Schneemeyer, L.F.; Waszczak, J.V.
Title Breakdown of the Meissner state in YBa$2$Cu$3$O7-? Type Conference Article
Year 1990 Publication (up) Transport properties of superconductors Abbreviated Journal
Volume Issue Pages 140
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Publisher World Scientific Place of Publication Singapore Editor Nicolsky, R.
Language Summary Language Original Title
Series Editor Series Title Progress in High Temperature Superconductivity Abbreviated Series Title
Series Volume 25 Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ hernan @ safar90 Serial 40
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